This invention relates to textured proteins. More specifically, the present invention provides a new process for preparing fibrous protein materials which can be used as, or in the production of, meat analogs.
In recent years, considerable research efforts have been focused upon developing new technology for producing meat-like, protein-containing foods from various vegetable and animal protein sources. Economics provides a major incentive. It would clearly be advantageous to substitute, at least in part, the more efficient process of growing vegetable protein for the rather inefficient process by which animals convert the proteinaceous vegetable materials into meat. This is especially true where the ever-increasing human population is feared to be out-distancing the availability of grazing land for meat-producing animals. Additionally, recent efforts have also been directed to avoiding certain natural products which may be undesirable for religous, ethnic, or health reasons.
All natural meats, including fish and poultry, have fibrous structures. The texture of the meat products is inherently dependent upon the fibrous nature of the meat. Likewise, the presence of a fibrous structure is an important factor in fabricated meat-like products. Thus, in producing these meat-like products, e.g. meat analogs, much effort has been directed to creating a fibrous structure, similar to natural meat. Many workers have developed a wide variety of techniques for obtaining fibrocity, and a good deal of published literature is available on the production of meat analogs with fibrous structures.
One early worker, Boyer, in U.S. Pat. No. 2,682,466 disclosed the formation of synthetic meat products containing quantities of vegetable protein filaments. These protein filaments are made by forcing a colloidal protein dispersion through a porous membrane, such as a spinnerette, into a coagulating bath causing precipitation of the protein in filament form. The filaments are assembled into a meat-like product by employing binding materials, including cereals and protein. The use of spun vegetable fibers enables the formation of a highly aligned fibrous structure. Unfortunately, the manufacture of spun fibers is complicated and relatively high in cost. Moreover, spun vegetable protein is generally poor nutritionally because the starting material depends on soy isolate.
In view of the difficulties inherent in spun fiber technology, other workers were encouraged to seek alternatives to this technique. One alternative, disclosed in U.S. Pat. No. 3,488,770, describes the production of a proteinaceous meat-like product having an open celled structure with cell length greater than cell width, and with the cells being substantially aligned. This product is made by extruding a dough, substantially free of non-proteinaceous filler, into an area of reduced pressure to cause expansion. Another alternative process working with a dough is disclosed in U.S. Pat. No. 3,693,533. According to that process, the protein containing dough is coagulated while being passed through a set of converging conveyors. The resulting stretching during coagulation produces what are described as unidirectional fibers. While these processes are potentially less costly than the spun fiber technology, they suffer a penalty in the quality of the fibers produced.
Several workers, in Japanese Pat. Nos. 48-21,502 and 48-34,228, and French Pat. Nos. 2,130,254 and 2,130,282, describe the production of fibrous protein masses by processes including freezing a protein solution or dispersion and heating the frozen mass to heat set the protein. These fibrous products are described as being meat-like.